The present invention pertains to an input circuit for a microwave receiving system.
It is known to utilize a parametric down converter in an input circuit of a receiving system, with the parametric down converter being indirectly coupled to the antenna receiving the microwave signals. The parametric down converter provides a signal, or forward, circuit path which passes the received signals and a reflective circuit in which a reflective signal returns from the remaining portion of the receiving system. The parametric down converter is generally coupled to the antenna via a circulator which blocks the reflected signal from returning to the antenna.